Saab 9-3 Cabrio 2006 just bought engine control unit defective

Good evening, everybody, I’m a Saab newcomer and also new here in the forum. I bought the convertible for the family, as Mopped drove bitsl has become dangerous… On the last Saturday after 10 days of standstill the convertible was bridged by the ADAC with banner booster. I then drove for a long time, but the ignition key did not turn any more. Then the curiosity. Bridging and a new battery on Tuesday brought nothing… I was stunned and got the car in Trier into S Then came after half an hour of the call. Central control unit is defective. Makes 1,200 euros… such a mess. The master said, used ones he does not build for warranty… Can I understand that so far. He said I can’t get past the Saab workshop anyway, because ECUs need to be adapted there.Then I read in the network of repairs of the ECUs. That’s even available with copying the data of the old ECU s. Now my question. Has anyone ever done this before? Would you advise me to invest the 1,200 euros or rather a repair? Greetings from Trier Thomas